Under what condition can the temperature of water provided by a tank-less heater exceed 140°F?

The temperature of water provided by a tank-less heater can exceed 140°F when protective valves are installed because these valves serve as safety devices designed to prevent overheating and overpressure. Typically, tank-less water heaters have built-in safety mechanisms, but additional protective measures like temperature and pressure relief (TPR) valves can further ensure safe operation. If the system is equipped with these protective devices, the heaters can be set to higher temperatures safely within the acceptable limits, thus allowing the output to potentially exceed 140°F without posing a significant risk of scalding or equipment failure.

In contrast, other conditions mentioned do not inherently contribute to raising the output temperature safely. Energy efficiency does not directly correlate with the maximum temperature; using a higher voltage can affect performance but is not a standard consideration for temperature limits; and having no obstructions may improve flow but doesn’t alter safety limits for water temperature.